High tension ignition system



Dec. 6, 1938. T, TOGNOLA 2,139,475

HIGH TENSION IGNITION SYSTEM Filed June 10, 1937 2 Sheets-Sheet l u nmlw "ml I. a I W Dec. 6, 1938. T. TOGNOLA HIGH TENSION IGNITION SYSTEMFiled June 10, 1937 2 Sheets-Sheet 2 Patented Dec. 6, 1938 HIGH TENSIONIGNITION SYSTEM Tullio Tognola, Sidney, N. Y., assignor to BendixAviation Corporation, South Bend, Ind., a corporation of DelawareApplication June 10, 1937, Serial No. 147,537

7 Claims.

The present invention relates to a high tension ignition system and moreparticularly to an arrangement for adapting ignition generating devicesfor satisfactory use in situations other than that for which they weredesigned.

It sometimes happens that it is desired to use an ignition generatorsuch as a magneto for the ignition of an engine having a less number ofcylinders than that for which the generator is designed. Thus it may bedesired to use a magneto designed to ignite a four-cylinder engine, foroperating a two-cylinder engine, or a threecylinder engine with degreeand degree spacing of its firing points. It is desirable in such casesthat the superfluous discharges of the magneto be dissipated in order toprevent unnecessary electrical stresses on the magneto coil, but thisdissipation of the charges should be without fire hazard and withoutcausing undue arcing at the distributor points.

Thus it has been proposed to use an external gap to lead off thedischarge from one of the distributor terminals of the magneto, but suchexternal gap constitutes a fire hazard. It has also been proposed tomerely ground the superfluous distributor terminal, but in that case thedischarge across the points of the distributor is very heavy so that thepoints are burned and caused to deteriorate.

It is an object of the present invention to providein a high tensionignition system an arrangement for effectively dissipating superfluousdischarges of the ignition generator.

It is another object to provide such a device in whichlthere are noexternal air gaps such as might create a fire hazard.

It is a further object to provide such a device in which arcing at thedistributor points is de-U creased rather-than increased.

It is another object to provide such a device in which the energy of thesuperfluous discharges is dissipated. as heat in a resistor element.

Further objects and advantages will be ap-' parent from the followingdescription taken in connection with the accompanying drawings in which:

Fig. 1 is an end elevation partly broken away and in vertical section ofa magneto incorporating a preferred embodiment of the invention;

Fig. 2 is a top view of a second embodiment of the invention; v

Fig. 3 is a longitudinal sectional view of a. distributor terminal andcable connection; and

Fig. 4 is a similar view of such'terminal incurporating a dischargedissipating device in accordance with the present invention.

Referring first to Fig. 1 of the drawings, there is illustrated aconventional type of four-cylinder magneto indicated generally bynumeral I incorporating a distributor mechanism 2 including a terminalblock 3 from which emerge the output cables 4, 5,6 and I.

In this embodiment of the invention, it is proposed to use thisfour-cylinder magneto to ignite a two-cylinder engine, and the outputcables 6 and I are accordingly arranged to conduct high tensiondischarges from the magneto to the engine, not illustrated, for thatpurpose. The two superfluous output cables 4 and 5 are, as hereillustrated, connected to a grounding device 8 comprising a metallicthimble 9 attached and grounded in any suitable way as indicated at IIto the frame of the magneto I and closed at its lower end by a metallicplug I2. An insulating bushing I3 is mounted in the upper end of thegrounding device 8 and carries a binding post I4 to which cables 4 and 5are attached.

Within the thimble 9 a resistor element I5 in theiorm of a cylindricalcartridge with terminal conductor caps is mounted with one cap I6 inengagement with the grounded plug I2, and the other cap I! in engagementwith the inner end of the binding post I4, either directly or by meansof suitable conductive spacing means I 8 so that the binding post isgrounded to the frame of the magneto through the resistor I5.-

Resistor I5 may be of any suitable commercial form of suflicientcurrent-carrying capacity to lead of! the discharge of the magneto, andsumcient resistance, to cause the major part of the energy oi. thedischarge to be dissipated as heat in the resistor rather than in theair gap of the distributor. 0n the other hand, the resistance issuiliciently low to prevent excessive electrostatic stresses on themagneto coil.

It has been found that suitable values for the resistor I5- are anenergy capacity of about one watt and a resistatnce of about one-fourthmegohm. It will be understood that these values can be varied withinrather wide limits so long as the conditions above set forth arefulfilled, the optimum arrangement being a matter of adaptation to theparticular installation.

It will be understood that the discharge dissipating device may beconnected in' other ways than as illustrated in Fig. 1. Thus a device ofthis character may be incorporated directly in the output terminal ofthe magneto as shown in Figs. 2 and 4. i

Fig. 2 shows the top 2| of a magneto having four output terminals, twoof which 22 and 23 are arranged to be connected by cables 24 and 25 tothe spark plugs of the engine to be ignited, while the other terminals26 and 21 are provided with energy-dissipating devices in accordancewith the present invention.

The output terminal isillustrated in section in Fig. 3 and comprises aninsulating shell 28 retained in the cover 2i of the magneto by ametallic thimble 29. A sliding contact 3| is mounted in the lower end ofthe shell 28 as by means of a socket member 36, and a nipple 32 forreceiving the end of the output cable is clamped to the upper end of theshell 28 by means of a nut 33.

In the exercise of the invention, a grounding resistance is inserted inthe terminal as shown in Fig. 4. As there illustrated, the nipple 32 isremoved and a resistor 34 is inserted with its lower conductive cap 35in engagement with the socket member 36 for the contact member 3 I, andthe upper terminal 31 of resistor 34 is received in a cap 38 ofconductive material threaded on the thimble 29.

It will be understood that the resistor 34 in this case is analogous tothe resistor l5 shown in Fig, 1 and performs its function similarly.

Although but two locations and arrangements of charge-dissipatingdevices have been shown and described in detail, it will be understoodthat other arrangements are possible and that various changes may bemade in the design and proportions of the parts without departing fromthe spirit ofthe invention as defined in the claims appended hereto.

What is claimed is:

1. In an ignition system, a high tension gener-' ator, means forconducting discharges therefrom to ignite an internal combustion engine,and means including a resistor for dissipating superfluous discharges ofthe generator.

2. In an ignition system, a high tension generator, means including adistributor for conducting discharges therefrom to the cylinders of anengine to be ignited, and means including a resistor for connectingcertain of the terminals of the distributor to the ground.

3. In an ignition system, a high tension gener ator, means including adistributor having a plurality of terminals for conducting dischargestherefrom to the spark plugs of an internal combustion engine, and meansincluding a resistor having a value lower than the initial resistance ofsuch spark plugs for grounding the superfluous terminals of thedistributor.

4. In an ignition system for internal'combustion engines, a high tensiongenerator, a distributor for the output thereof having a plurality ofterminals, and means including a resistor having a value ofapproximately one-fourth megohm forming a ground connection for certainof the terminals of said distributor.

5. In an ignition system for internal combustion engines, a high tensiongenerator, and means adapting said generator for use with engines havinga smaller number of cylinders than that for which the generator isdesigned, including a resistor for grounding the superfluous dischargesof the magneto, said resistor having a value during such dischargesgreater than the resistance of the remainder of the path of suchdischarges.

6. In combination with a magneto having a distributor with a pluralityof output terminals, a resistor grounding certain 9f said terminalshaving a value low enough to relieve the magneto from undue electricalstress, but high enough to prevent burning the distributor points.

7. In an ignition system, a high tension generator, means including adistributor having a rotary conductor finger and a plurality of outputconductors terminating adjacent the path of said finger for conductingdischarges therefrom to the spark plugs of an internal combustionengine, and means including a resistor having a value greater than theresistance of the air gap between the finger and its adjacent outputconductor of the distributor while a discharge is occurring forconnecting certain of the output conductors to the ground.

TULLIO 'I'OGNOLA.

